Compilare: user.cpp: In function ‘int main()’: user.cpp:20:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 2; i < a.size(); ++ i){ ^ user.cpp:29:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < b.size(); ++i){ ^ user.cpp:32:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(q == a.size()-1){ ^